最近在安装SASS的时候，用到gem命令，但是运行出行如下错误！
C:\Users\len>gem install sass
ERROR: While executing gem ... (Gem::RemoteFetcher::FetchError)
Errno::ETIMEDOUT: A connection attempt failed because the connected party di
d not properly respond after a period of time, or established connection failed
because connected host has failed to respond. - connect...